EAL

H/A: Body Composition Measurement (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate the ability of standard bioelectrical impedance analysis equations to predict total body water and fat free mass in children with HIV infection and to develop equations specifically for this population, if necessary.

Inclusion Criteria:

Pre-pubertal children, age four years to 11 years, with HIV infection as defined by the Centers for Disease Control and Prevention.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

Pre-pubertal children were recruited from the St. Luke's-Roosevelt Hospital Center Pediatric HIV/AIDS Program. Methods not described.

Design

Cross-sectional study.

Statistical Analysis

Values predicted by the equations were compared with measured values using paired T-tests
New equations were derived for total body water and fat-free mass with the use of regression techniques
The set of independent variables considered for inclusion in the model were height²/resistance, height²/reactance, weight and age
Residual analyses were done on the final equations.

Data Collection Summary:

Timing of Measurements

All measurements done after an overnight fast.

Dependent Variables

Weight to the nearest 0.01kg obtained with a beam-balance scale
Height to the nearest 0.01cm obtained with a fixed wall-mounted stadiometer
Total body water measured by means of deuterium oxide dilution
Fat-free mass measured with total body dual-energy X-ray absorptiometry
Total body resistance and reactance measured with bioelectrical impedance analysis
Total body water and fat-free mass also predicted by eight published prediction equations.

Independent Variable

HIV infection.

Description of Actual Data Sample:

Initial N: 20 prepubertal children: 9 boys, 11 girls

Attrition (final N): 20 children

Age: Four years to 11 years; mean 6.5 years±2.3 years

Ethnicity: Six (30%) were black, 14 (70%) were Hispanic

Other relevant demographics: No information about medications provided

Biochemical data: Mean CD4+ count, 319 cells per dL±330 cells per dL (range 4 cells per dL to 1,099 cells per dL); mean CD4+ percentage, 16.8%±13.8% (range 0.6% to 40.4%)

Location: New York, NY.

Summary of Results:

Study, n	Body Compartment	Predicted Weight (kg)	Predicted-measured (kg)	P-value
Fjeld et al, n=30	TBW	12.95±4.1	0.75	0.02
Danford et al, n=37	TBW	12.81±3.94	0.88	0.009
Davies et al, n=26	TBW	10.61±3.64	3.03	0.001
Gregory et al, n=34	TBW	11.03±3.3	-2.67	0.001
Davies and Gregory, n=60	TBW	10.93±3.5	-2.77	0.001
Deurenberg et al, n=827	FFM	16.08±4.88	-2.28	0.001
Cordain et al, n=30	FFM	21.75±4.82	3.39	0.001
Houtkooper et al, n=94	FFM	19.69±4.93	1.33	0.001

Other Findings

The use of standard prediction equations resulted in substantial error.

Regression equations using height and bioelectrical impedance analysis resistance for estimating total body water and fat-free mass were developed and seem to improve accuracy of prediction.

Author Conclusion:

This study suggests that total body water and fat-free mass can be estimated in children with HIV by means of bioelectrical impedance analysis equations specifically developed for use with this group of children. Our results indicate that standard equations established for predicting body composition from bioelectrical impedance analysis-derived measurements in children are not valid for application to children with HIV infection.

Funding Source:

Government:

NIH grant DK 37352

Reviewer Comments:

Recruitment methods not described. Authors note that sample size was not adequate for evaluating the effects of race, stage of disease and secondary conditions (e.g., growth disturbances, opportunistic infections, renal disease and cardiac disease) on this model.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	N/A
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	N/A

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		???
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	Yes
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		Yes
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	Yes
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	Yes
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	N/A
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	N/A
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		???
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	Yes
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	No
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes